...Two fifths of the subs that ventured into the Mediterranean were sunk and when a submarine sank it became a communal coffin - everyone on board died. That was the rule.In fact, during the whole of the war there were only four escapes from stricken British submarines. And the most remarkable of these took place on 6 December 1941, when HMS Perseus plummeted to the seabed...He dragged any stokers who showed signs of life towards the escape hatch and fitted them and himself with Davis Submarine Escape Apparatus, a rubber lung with an oxygen bottle, mouthpiece and goggles.This equipment had...